Exploring Interactions of Cloudiness, Solar Forcing and North Atlantic Circulation in Mediterranean Climate Variability

Multi‐decadal changes in solar activity and cloudiness significantly influence Earth's climate, yet their pre‐industrial dynamics (before 1900) remain poorly understood. This study explores the relationship between total cloud cover (TCC), solar forcing, and mean annual temperature variability in the Mediterranean region, focusing on both the pre‐industrial and the modern era (1982–2022). Leveraging 41 years of contemporary cloud data from the European Organisation for the Exploitation of Meteorological Satellites and historical records from Italy's Benevento Observatory (dating back to 1870), we identify a marked decline in annual TCC across both periods, coupled with rising mean temperatures. Regional analyses highlight substantial disparities in TCC reductions, with declines of up to 10% per decade in Sicily (Italy) and northern Tunisia. A pivotal change‐point in cloud dynamics emerges around 2001, marked by a transition in the relationship between galactic cosmic rays (GCRs) and TCC from consistent positive correlations (1982–2001) to spatially varied patterns thereafter. This shift coincides with a notable reduction in high‐cloud coverage (HCC) over the central and eastern Mediterranean. While causality remains uncertain, correlations point to GCRs and North Atlantic thermohaline circulation (NA‐THC) anomalies as potential modulators of regional cloud dynamics. Contrasting pre‐industrial ( r = 0.46) and modern ( r = −0.69) correlations underscore the complexity of cloud cover responses, highlighting the role of atmospheric circulation and the need for further investigation into these dynamics and their implications for climate variability.